SLVSER4B May 2020 – January 2022 TPS92200
PRODUCTION DATA
When LED+ and LED– are shorted, VFB is higher than internal reference voltage, VREF, and internal error amplifier output voltage VCOMP is driven low and clamped. The high-side MOSFET is forced to turn on with the minimum on-time each cycle, tMIN_ON. In this case, if the output voltage is too low, the inductor current cannot balance in a cycle, causing current runaway. Finally, the inductor current is clamped by low-side MOSFET sourcing current limit ILIM_LS_SOUR which is 3-A typical. If VFB rises higher than VFB_OVP, the device starts the auto-retry timer. After the counter, tRETRY_ON, expires, the device shuts down and starts another counter, tRETRY_OFF. During the shutdown period, both high-side and low-side MOSFETs are turned off. After the hiccup timer expires, TPS92200 restarts again. The device repeats these behaviors until the failure condition is removed. During the auto-retry mode, the device is also protected by the overcurrent limits of both high-side power switch and low-side power switch.